共查询到20条相似文献,搜索用时 15 毫秒
1.
B. Terhalle A.S. Desyatnikov C. Bersch D. Träger L. Tang J. Imbrock Y.S. Kivshar C. Denz 《Applied physics. B, Lasers and optics》2007,87(3):559-563
Table grapes were irradiated with UV nanosecond laser pulses in searching for resonant photo-elicitation of trans-resveratrol, a known antioxidant compound naturally produced by grapevines and other plants. To this end, the irradiation
time as well as the wavelength dependence of the induced trans-resveratrol content was investigated by comparing the elicitation level of this compound at two laser wavelengths. One wavelength
was selected right at the maximum of the absorption band (302.1 nm, the resonant wavelength for this compound) while the second
was selected (300 nm, a non-resonant wavelength) such that trans-resveratrol absorption is negligible. It was found that the resonant irradiation enhances the resveratrol content in grapes
by up to six times more than that of non-resonant irradiation, the rest of the conditions being the same. This work demonstrates
how selective laser excitation of fruits can open new possibilities for the development of functional foods with enhanced
nutritional and beneficial properties.
PACS 42.62.-b; 82.50.Hp 相似文献
2.
3.
D. Mihalache D. Mazilu F. Lederer 《The European physical journal. Special topics》2009,173(1):255-266
In the framework of the continuous-discrete cubic-quintic Ginzburg-Landau model, spatiotemporal dissipative solitons which
are highly confined inside two-dimensional photonic lattices are found numerically. The domains of existence in the relevant
parameter space, of in-phase (unstaggered) on-site (single-peaked), inter-site (double-peaked), and flat-top-like (four-peaked)
spatiotemporal dissipative solitons are determined. We show that the on-site solitons are stable in the whole domain of their
existence and we find the stability domains of both inter-site and flat-top-like solitons. We describe the complex instability-induced
scenarios of the dynamics of spatiotemporal discrete Ginzburg-Landau solitons in two-dimensional photonic lattices. 相似文献
4.
Neshev DN Alexander TJ Ostrovskaya EA Kivshar YS Martin H Makasyuk I Chen Z 《Physical review letters》2004,92(12):123903
We report on the first experimental observation of discrete vortex solitons in two-dimensional optically induced photonic lattices. We demonstrate strong stabilization of an optical vortex by the lattice in a self-focusing nonlinear medium and study the generation of the discrete vortices from a broad class of singular beams. 相似文献
5.
Theoretical results on spatial optical bright solitons excited in arrays of nonlinear defocusing
waveguides, that result from the photovoltaic effect in a photorefractive material, are presented. The existence
of four types of stationary discrete bright staggered solitons, on-site, inter-site, twisted inter-site, and
twisted on-site solitons, is shown both analytically and numerically, and their stability properties are
investigated. The maximum Hamiltonian of staggered solitons with the same total power corresponds to stable modes.
It is shown that for low total power the on-site mode is stable while in the high power regime the inter-site mode
is stable. These results are confirmed numerically. In addition, steering properties of localized modes are
investigated by introducing a transversal translational shift. Because of the translational symmetry between
on-site and inter-site localized modes they are considered as two dynamical realizations of the same moving mode,
and the formalism of the Peierls-Nabarro effective potential is applied to interpret the exchange between trapping
and steering of these modes. This critically depends on the mode’s total power and the introduced phase
difference. On the other hand, steering of twisted inter-site and on-site localized modes is not numerically
observed. Instead, transversal perturbation leads to a transformation of twisted modes either into a trapped
on-site mode of smaller power and radiation, or into two trapped on-site modes. 相似文献
6.
Systematic results of collisions between discrete spatiotemporal dissipative Ginzburg-Landau solitons in two-dimensional photonic
lattices are reported. The generic outcomes are identified for (i) the collision of two identical solitons located in the
corner, at the edge, and in the center of the photonic lattice, and for (ii) the collision of two non-identical corner and
edge solitons located at different distances from the boundaries of the photonic lattice. Depending on the values of the kick
(collision momentum) and of the nonlinear (cubic) gain, the collision scenarios include soliton merging, creation of an extra
soliton, soliton bouncing, soliton spreading, and quasi-elastic (symmetric) interactions. 相似文献
7.
Fleischer JW Bartal G Cohen O Manela O Segev M Hudock J Christodoulides DN 《Physical review letters》2004,92(12):123904
We present the experimental observation of both on-site and off-site vortex-ring solitons of unity topological charge in a nonlinear photonic lattice, along with a theoretical study of their propagation dynamics and stability. 相似文献
8.
We study surface modes at the edge of a semi-infinite chirped photonic lattice in the framework of an effective discrete nonlinear model. We demonstrate that the lattice chirp can change dramatically the conditions for the mode localization near the surface, and we find numerically the families of discrete surface solitons in this case. Such solitons do not require any minimum power to exist provided the chirp parameter exceeds some critical value. We also analyze how the chirp modifies the interaction of a soliton with the lattice edge. 相似文献
9.
We introduce a novel class of stable lattice solitons with a complex phase structure composed of many single-charge discrete vortices in a triangular photonic lattice. We demonstrate that such nonlinear self-trapped states are linked to the resonant Bloch modes, which bear a honeycomb pattern of phase dislocations. 相似文献
10.
Fischer R Träger D Neshev DN Sukhorukov AA Krolikowski W Denz C Kivshar YS 《Physical review letters》2006,96(2):023905
We demonstrate theoretically and experimentally a novel type of localized beam supported by the combined effects of total internal and Bragg reflection in nonlinear two-dimensional square periodic structures. Such localized states exhibit strong anisotropy in their mobility properties, being highly mobile in one direction and trapped in the other, making them promising candidates for optical routing in nonlinear lattices. 相似文献
11.
Spatial solitons in photorefractive media 总被引:5,自引:0,他引:5
12.
We demonstrate that interfaces between two nonlinear periodic photonic lattices offer unique possibilities for controlling the nonlinear interaction between different spectral components of polychromatic light, and a change in the light spectrum can have a dramatic effect on the propagation along the interface. We predict the existence of polychromatic surface solitons that differ fundamentally from their counterparts in infinite lattices. 相似文献
13.
We analyze spatiotemporal light localization in truncated two-dimensional photonic lattices and demonstrate the existence of two-dimensional surface light bullets localized in the lattice corners or the edges. We study the families of the spatiotemporal surface solitons and their properties such as bistability and compare them with the modes located deep inside the photonic lattice. 相似文献
14.
The existence and general properties of different kinds of defect vector gap solitons in one dimensional optically induced photonic defect lattice with focusing saturable nonlinearity in photorefractive crystal are analyzed. The defect is well localized in a single site with two existence forms, namely repulsive and attractive defect. Propagation constants of two beams that compose defect vector gap solitons could be from same gap or from different gaps. We show that some kinds of unstable scalar defect gap solitons could be stabilized by their corresponding vector cases. 相似文献
15.
光子晶格作为一种光学周期性离散体系,具有通常均匀介质所无法比拟的独特性质,它为空间离散孤子、表面波以及衍射操控等一系列线性和非线性离散动力学行为的实验观测提供了便利条件,同时在全光路由、全光开关和光子计算机等方面具有重要的应用前景.文章简要回顾了南开大学的研究小组近期在二维光子晶格中有关空间带隙孤子的一系列研究工作,包括二维基本带隙孤子、类偶极带隙孤子、带隙孤子串以及涡旋带隙孤子等.在有的实验过程中,文章作者清晰地观测到探测光束的频谱整形,波常数从具有反常衍射的导带底部演化到光子禁带中,并且通过干涉图反映的相位关系验证了带隙孤子形成.实验的结果可以为其他离散系统中带隙孤子态的观测提供有益参考和启示. 相似文献
16.
Terhalle B Richter T Desyatnikov AS Neshev DN Krolikowski W Kaiser F Denz C Kivshar YS 《Physical review letters》2008,101(1):013903
We report on the first observation of topologically stable spatially localized multivortex solitons generated in optically induced hexagonal photonic lattices. We demonstrate that topological stabilization of such nonlinear localized states can be achieved through self-trapping of truncated two-dimensional Bloch waves and confirm our experimental results by numerical simulations of the beam propagation in weakly deformed lattice potentials in anisotropic photorefractive media. 相似文献
17.
Yang J Makasyuk I Kevrekidis PG Martin H Malomed BA Frantzeskakis DJ Chen Z 《Physical review letters》2005,94(11):113902
We report the first observation of stationary necklacelike solitons. Such necklace structures were realized when a high-order vortex beam was launched appropriately into a two-dimensional optically induced photonic lattice. Our theoretical results obtained with continuous and discrete models show that the necklace solitons resulting from a charge-4 vortex have a pi phase difference between adjacent "pearls" and are formed in an octagon shape. Their stability region is identified. 相似文献
18.
光子晶格作为一种光学周期性离散体系,具有通常均匀介质所无法比拟的独特性质,它为空间离散孤子、表面波以及衍射操控等一系列线性和非线性离散动力学行为的实验观测提供了便利条件,同时在全光路由、全光开关和光子计算机等方面具有重要的应用前景.文章简要回顾了南开大学的研究小组近期在二维光子晶格中有关空间带隙孤子的一系列研究工作,包括二维基本带隙孤子、类偶极带隙孤子、带隙孤子串以及涡旋带隙孤子等.在有的实验过程中,文章作者清晰地观测到探测光束的频谱整形,波常数从具有反常衍射的导带底部演化到光子禁带中,并且通过干涉图反映 相似文献
19.
Spatial solitons in centrosymmetric photorefractive media 总被引:5,自引:0,他引:5
We predict spatial solitons in photorefractive centrosymmetric media driven by the dc Kerr effect. 相似文献
20.
The effect of the formation of spatial gap solitons within one-dimensional optically induced photo-refractive photonic lattices in iron-doped lithium niobate is experimentally investigated. Mutually incoherent Bragg-matched beams with optical powers in the microwatt range from two different He-Ne lasers are used to generate immobile spatial gap solitons within the lattice with a spatial period of 15 μm. 相似文献